Dispensing Fluid from an Infusion Pump System

ABSTRACT

Some embodiments of an infusion pump device may include a drive system that accurately and incrementally dispenses fluid from the pump device in a controlled manner. Particular embodiments of the drive system may include a rotational motor that is coupled to a string member, which is used to adjust a pawl relative to a ratchet body. In such circumstances, the drive system can provide a reliable and compact infusion pump device that accurately dispenses the desired volume of fluid.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. application Ser.No. 12/422,711, filed on Apr. 13, 2009, which is a divisionalapplication of U.S. application Ser. No. 11/522,560, filed on Sep. 18,2006, which claims priority to (1) U.S. Provisional Application Ser. No.60/720,411 filed on Sep. 26, 2005 by Mernoe et al. and entitled“Precision Drive Mechanism,” (2) U.S. Provisional Application Ser. No.60/720,405 filed on Sep. 26, 2005 by Mernoe et al. and entitled“Flexible Pushrod Mechanism,” and (3) U.S. Provisional Application Ser.No. 60/721,267 filed on Sep. 28, 2005 by Estes et al. and entitled“Infusion Pump with Removable Controller.” The entire contents of theseprior applications are fully incorporated by reference herein.

TECHNICAL FIELD

This document relates to an infusion pump system, such as a medicalinfusion pump system.

BACKGROUND

Pump devices are commonly used to deliver one or more fluids to atargeted individual. For example, a medical infusion pump device may beused to deliver a medicine to a patient as part of a medical treatment.The medicine that is delivered by the infusion pump device can depend onthe condition of the patient and the desired treatment plan. Forexample, infusion pump devices have been used to deliver insulin to thevasculature of diabetes patients so as to regulate blood-glucose levels.

A number of factors may affect the design of infusion pump devices. Onesuch factor is the size of the device. The device may be sized to housethe various pump components, yet a large device may reduce theportability for the user. Another factor that may affect the design ofan infusion pump device is the convenience to the user. For example, ifthe device is designed to be a reusable dispenser having high-costcomponents, it may be expensive and inconvenient for the user to replacesuch a device that has been lost or damaged. A number of infusion pumpcomponents can impact the overall size of the device and the convenienceto the user.

SUMMARY

Some embodiments of an infusion pump device may include a drive systemthat accurately and incrementally dispenses fluid from the pump devicein a controlled manner. Particular embodiments of the drive system mayinclude a rotational motor that is coupled to a string member, which isused to adjust a pawl member relative to a ratchet body. This operationof the drive system may cause incremental longitudinal advancement of apiston rod in the infusion pump device, which forces a controlled amountof fluid from the pump device. In such circumstances, the drive systemcan be part of a reliable and compact infusion pump device thataccurately dispenses the desired volume of fluid.

In some embodiments, a medical infusion pump system may include a pumpdevice having a drive system to cause dispensation of a medicine. Thedrive system may include a pawl that is adjustable relative to a ratchetbody. The pawl may engage one or more teeth of the ratchet body toincrementally advance the ratchet body. The drive system may alsoinclude a string member coupled to the pawl. The string member may bearranged in a loop around two or more guide structures. The drive systemmay further include a rotational motor coupled to the string member sothat rotation by the motor causes the string member to adjust the pawlrelative to the ratchet body. In certain aspects, the medical infusionpump system may include a removable controller device that ismechanically and electrically connectable to the pump device.

Particular embodiments of a medical infusion pump system may include apump device having a drive system to cause dispensation of a medicine.The drive system may include a pawl that is adjustable relative to aratchet body. The pawl may engage one or more teeth of the ratchet bodyto incrementally advance the ratchet body. The drive system may alsoinclude a flexible member coupled to the pawl and a spindle coupled tothe flexible member. The drive system may further include a rotationalmotor coupled to the spindle so that rotation by the motor causes theflexible member to wind or unwind around spindle to thereby adjust thepawl relative to the ratchet body.

Some embodiments of a medical infusion pump system may include a pumpdevice and a controller device that is electrically connectable to thepump device to control operation of the drive system. The pump devicemay include a housing that defines a cavity to receive a medicine and adrive system to cause dispensation of the medicine when the medicine isreceived in the cavity. The drive system may include a rotational motorand a string member coupled to the motor. The string member may comprisebraided filaments.

In certain embodiments, a method for dispensing medicine from aninfusion pump system includes rotating a motor one or more fullrotations in a first rotational direction to unwind a string member froma spindle and thereby adjust a ratchet mechanism coupled to a pistonrod. The adjustment of the ratchet mechanism may incrementally advancethe piston rod in a forward direction to force medicine from a wearablemedicine dispenser device. The method may also include continuing torotate the motor in the first rotational direction so that the stringmember winds around the spindle and thereby applies a tension force toreset the ratchet mechanism. The method may include, in a nextdispensing cycle, rotating the motor one or more full rotations in anopposite, second rotational direction to unwind the string member fromthe spindle and thereby adjust the ratchet mechanism coupled to thepiston rod. The adjustment of the ratchet mechanism may incrementallyadvance the piston rod in the forward direction to force medicine fromthe wearable medicine dispenser device.

Some embodiments of a method for dispensing medicine from an infusionpump system may include rotating a motor to unwind a string member froma spindle and thereby adjust a ratchet mechanism coupled to a pistonrod. The adjustment of the ratchet mechanism may incrementally advancethe piston rod in a forward direction to force medicine from a wearablemedicine dispenser device. The method may also include rotating themotor to wind the string member around the spindle and thereby apply atension force to reset the ratchet mechanism.

These and other embodiments may provide one or more of the followingadvantages. First, the drive system of the pump device can provide areliable and consistent configuration for accurately dispensing thedesired volume of fluid from the pump device. Second, some embodimentsof the drive system may comprise few, if any, high-cost components,thereby facilitating the production of a disposable infusion pumpdevice. Third, the pump device may house the drive system in a compactmanner so that the pump device is portable, wearable, and readilyconcealable by the user. As such, a user can conveniently wear the pumpdevice on the user's skin underneath clothing or carry the pump devicein the user's pocket (or other portable location) while receiving themedicine dispensed from the pump device. Fifth, in some embodiments, astring member of the drive system can be arranged in a loop around twoor more guides so as to optimize the location and direction of the forceapplied by the string member and to provide a force amplificationeffect. Sixth, the string member of the driver system may comprisebraided filaments that are capable of enduring the torsion andfrictional forces associated with undergoing a multitude of motioncycles. Seventh, some embodiments of the infusion pump system mayinclude a removable controller device having a user interface. Such aconfiguration may provide the user with the ability to monitor thedevice settings by simply viewing the pump device (e.g., no need for aseparate device for reviewing the pump settings). Moreover, theremovable controller configuration may provide the user with the abilityto dispose of the pump body while reusing the removable controller witha new, subsequent pump body (e.g., maintaining the previous usersettings while receiving a new supply of medicine). Eighth, the pumpdevice can be configured to receive a preloaded medicine cartridge(e.g., preloaded with insulin or another medicine for use in thetreatment of Diabetes) so as to facilitate low manufacturing costs andhigh speed assembly.

The details of one or more embodiments of the invention are set forth inthe accompanying drawings and the description below. Other features,objects, and advantages of the invention will be apparent from thedescription and drawings, and from the claims.

DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of an infusion pump system, in accordancewith some embodiments.

FIG. 2 is an exploded perspective of the pump device of FIG. 1.

FIG. 3A is a diagram of a portion of the pump device of FIG. 1.

FIG. 3B is a magnified view of a string member of FIG. 3A.

FIG. 3C is a perspective view of the portion of the pump device of FIG.3A.

FIG. 4 is an exploded perspective view of a portion of an infusion pumpdevice, in accordance with some embodiments.

FIG. 5 is a perspective view of the portion of the infusion pump deviceof FIG. 4.

FIGS. 6-7 are perspective views of an infusion pump system including theinfusion pump device of FIG. 4.

FIG. 8 is a perspective view of a drive system of the infusion pumpdevice of FIG. 4.

FIG. 9 is a perspective view of the drive system of FIG. 4 in a firstposition.

FIG. 10 is a perspective view of the drive system of FIG. 4 in a secondposition.

FIGS. 11A-C are perspective views of a portion of the infusion pumpdevice of FIG. 4.

FIG. 12 is a diagram of a portion of an infusion pump device, inaccordance with some embodiments.

FIG. 13 is a perspective view of a portion of the infusion pump device,in accordance with some embodiments.

FIG. 14 is a perspective view of a drive system of the infusion pumpdevice of FIG. 13.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Referring to FIG. 1, some embodiments of an infusion pump system 10include a pump device 100 that can communicate with a controller device200. The pump device 100 includes a housing structure 110 that defines acavity 116 in which a fluid cartridge 120 is received. In thisembodiment, the pump system 10 in a medical infusion pump system that isconfigured to controllably dispense a medicine from the cartridge 120.As such, the fluid cartridge 120 may contain a medicine to be infusedinto the tissue or vasculature of a targeted individual, such as a humanor animal patient. For example, the pump device 100 can be adapted toreceive a medicine cartridge 120 in the form of carpule that ispreloaded with insulin or another medicine for use in the treatment ofDiabetes (e.g., Byetta®, Symlin®, or others). Such a cartridge 120 maybe supplied, for example, by Eli Lilly and Co. of Indianapolis, Ind.Other examples of medicines contained in the fluid cartridge 120include: pain relief drugs, hormone therapy, blood pressure treatments,anti-emetics, osteoporosis treatments, or other injectable medicines.

As described in more detail below, the pump device 100 includes a drivesystem that causes controlled dispensation of the medicine or otherfluid from the cartridge 120. In some embodiments, the drive system (notshown in FIG. 1) incrementally advances a piston rod longitudinally intothe cartridge 120 so that the fluid is forced out of the output end 122(described below). In this embodiment, the septum at the output end 122can be pierced to permit fluid outflow when a cap member (not shown inFIG. 1, refer to cap member 315 in FIG. 5 for one example) is connectedto the pump housing structure 110.

The drive system may be housed in the housing structure 110 of the pumpdevice in a compact manner so that the pump device 100 is portable,wearable, concealable, or a combination thereof. For example, in thecircumstances in which the medicine cartridge 120 has a length of about6 cm to about 7 cm (about 6.4 cm in this embodiment), the overall lengthof the pump housing structure 110 (which contains medicine cartridge andthe drive system) can be about 7 cm to about 9 cm (about 8.3 cm or lessin this embodiment). In addition, the pump housing structure 110 mayhave an overall height of about 1.5 cm to about 4 cm (about 2.9 cm orless in this embodiment) and an overall thickness of about 8 mm to about20 mm (about 14.5 mm or less in this embodiment). Accordingly, a usercan conveniently wear the pump device 100 on the user's skin (e.g., skinadhesive) underneath the user's clothing or carry the pump device 100 inthe user's pocket (or other portable location) while receiving themedicine dispensed from the pump device.

For example, in the circumstances in which the medicine cartridge 120has a length of about 6 cm to about 7 cm (about 6.4 cm in thisembodiment), the overall length of the pump housing structure 110 (whichcontains medicine cartridge and the drive system) can be about 7 cm toabout 9 cm (about 8.3 cm or less in this embodiment). In addition, thepump housing structure 110 may have an overall height of about 1.5 cm toabout 4 cm (about 2.9 cm or less in this embodiment) and an overallthickness of about 8 mm to about 20 mm (about 14.5 mm or less in thisembodiment). In such circumstances, the controller device 200 can befigured to mate with the compact pump housing structure 110 so that,when removably attached to one another, the components define a portableinfusion pump unit that stores a relatively large quantity of medicinecompared to the overall size of the unit. For example, in thisembodiment, the infusion pump system 10 (including the pump device 100attached to the removable controller device 200) may have an overalllength of about 7 cm to about 9 cm (about 8.5 cm or less in thisembodiment), an overall height of about 1.5 cm to about 4 cm (about 3.5cm or less in this embodiment), and an overall thickness of about 8 mmto about 20 mm (about 15 mm or less in this embodiment).

Still referring to FIG. 1, the drive system of the pump device 100 maybe continuously or intermittently controlled by pump controller device200. In this embodiment, the controller device 200 is configured toremovably attach to the pump device 100, When attached, the controllerdevice 200 communicates electronic control signals viahard-wire-connection to the drive system or other components of the pumpdevice 100. The controller device 200 can include a controller housingstructure 210 that is configured to mate with a complementary portion ofthe pump housing structure 110 so as to form a releasable mechanicalconnection. For example, the pump housing structure 110 may define acavity 118 that mates with a complementary protruding face (not show inFIG. 1) of the controller housing structure 210 for a friction fitengagement. Also, the controller housing structure 210 may include achannel 212 that mates with a curved surface 117 of the pump housingstructure 110 when the controller device 200 is attached to the pumpdevice. In addition, one or more releasable connector devices (e.g.,mating tongues and grooves, mounting protrusions friction fit intomating cavities, or the like) can be used to further implement thereleasable securement of the controller device 200 to the pump device100. Furthermore, the pump device 100 may include one or more electricalcontacts 118 that are exposed to the controller device 200 and that matewith opposing electrical contacts (e.g., conductive pads, pins, and thelike) on the adjacent face of the controller device 200. As such, thecontroller device 200 is in electrical communication with the pumpdevice 100 and is capable of transmitting electrical signals to the pumpdevice 100 and receiving feedback signals (e.g., sensor signals) fromcomponents within the pump device 100.

The pump controller device 200 includes a user interface 220 thatpermits a user to monitor the operation of the pump device 100. In thisembodiment, the user interface includes a display 222 and one or moreuser-selectable buttons 224, 226, and 228. The display 222 may be usedto communicate a number of settings or menu options for the infusionpump system 10. For example, the user may press one or more of thebuttons 224, 226, and 228 to shuffle through a number of menus orprogram screens that show particular settings and data (e.g., reviewdata that shows the medicine dispensing rate or the total amount ofmedicine dispensed in a given time period). Also, in some embodiments,the user can adjust the settings or otherwise program the controllerdevice 200 by pressing one or more buttons 224, 226, and 228 of the userinterface 220. In embodiments of the infusion pump system 10 configuredto dispense insulin, the user may press one or more of the buttons 224,226, and 228 to change the dispensation rate of insulin or to requestthat a bolus of insulin be dispensed. In some embodiments, the userinterface 220 may include tactile buttons, a touch screen, audio inputsor outputs, or a combination thereof. Previously incorporated U.S.Provisional Application Ser. No. 60/721,267 also describes a number ofconfigurations for a removable controller device in addition to theconfiguration illustrated in FIG. 1 herein.

Accordingly, when the controller device 200 is connected to the pumpdevice 100, the user is provided with the opportunity to readily monitorinfusion pump operation by simply viewing the user interface 210connected to the pump device 100. Such monitoring capabilities mayprovide comfort to a user who may have urgent questions about thecurrent operation of the pump device 100 (e.g., the user may be unableto receive immediate answers if wearing an infusion pump device havingno user interface attached thereto). Also, there is no need for the userto carry and operate a separate device to monitor the operation of theinfusion pump device 100, thereby simplifying the monitoring process andreducing the number of devices that must be carried by the user.

Referring to FIG. 2, the pump device 100 includes a drive system 105that accurately and incrementally dispenses fluid from the pump device100 in a controlled manner. In this embodiment, the pump housingstructure 110 includes a detachable shell 112 that covers at least aportion of the drive system 105 and includes a frame portion 114 towhich at least a portion of the drive system 105 is mounted. Thedetachable shell 112 may include an inner curved surface against which acurved section of a piston rod 170 rests. The frame portion 114 define athe cavity 116 that receives the fluid cartridge 120. One or both of thedetachable shell 112 and the frame portion 114 can be molded frompolymer material, such as Polycarbonate, Acrylonitrile ButadieneStyrene, or Acrylic. As previously described, in some embodiments, thefluid cartridge 120 may occupy a majority of the length of the pumpdevice 100 (with the drive system 105 being arranged in a compactmanner) so that the pump device 100 is wearable and portable.

In some embodiments, the drive system 105 may include a rotational motor130 that is coupled to a string member 140, which is used to adjust aratchet mechanism 150. Briefly, the rotational motor 130 can be used toact upon the string member 140, thereby causing the string member 140 toadjust a pawl member 152 relative to a ratchet body 155. In thisembodiment, the ratchet body 155 is in the form of a ratchet wheel. Theratchet wheel 155 can be integrally formed with, or mounted to, a wormgear 156. Incremental rotation of the ratchet wheel 155 causes rotationof a drive wheel 160 (due to engagement with the worm gear 156), whichcauses the incremental longitudinal advancement of a flexible piston rod170. As the piston rod 170 is advanced into plunger chamber 126 of thefluid cartridge 120 (e.g., defined in this embodiment by thecircumferential wall 124 of the fluid cartridge 120), the fluid in thecartridge 120 is forced from the septum at the output end 122. It shouldbe understood from the description herein that, when the pump device 100is in use, the septum at the output end 122 may be pierced by a capmember (not shown in FIG. 2) mounted to the housing structure 110, whichallows fluid to exit from the cartridge 120 and enter a tube of aninfusion set attached to the patient. Accordingly, the drive system 105can provide a reliable and compact configuration for accuratelydispensing the desired volume of fluid from the pump device 100.Moreover, the drive system 105 may comprise few, if any, high-costactuator components or electronics, thereby facilitating the relativelylow-cost production of a disposable and reliable pump device 100.

Referring now to the components of the drive system 105 in more detail,the rotational motor 130 may comprise a battery powered actuator havinga rotatable output shaft 132. In this embodiment, the rotational motor130 can receive signals that cause the output shaft to rotate in a firstrotational direction or in a second, opposite rotational direction. Oneexample of a suitable rotational motor 130 is a coreless DC motorsupplied by Jinlong Machinery of China.

The rotational motor 130 can be mounted to the frame portion 114 of thepump housing structure 110 so that the motor 130 remains in asubstantially stationary position relative to the electrical contacts119 of the pump device 100. As such, the operation of the rotationalmotor 130 can be controlled by the control device 200 (FIG. 1) viaelectrical signals communicated through one or more of the electricalcontacts 119. In some embodiments, one or more of the electricalcontacts 119 may be directly connected to the inputs of the rotationmotor 130, for example, to deliver control signals from a controlcircuit or to deliver electrical current from a battery, capacitor, orother power source disposed in the controller device 200 or disposed inthe pump device 100. In other embodiments, the electrical contacts 119may be connected to an electrical circuit (e.g., an integrated circuitimplemented on a small printed circuit board) onboard the pump device100 (e.g., mounted to the frame portion 114). In such circumstances, thecontrol device 200 may deliver control signals via the electricalcontacts 119 to the electrical circuit onboard the pump device 100,which then opens a gate or a circuit pathway to permit the electricalcurrent to pass to the rotational motor 130 (e.g., from a battery orother power source disposed in the pump device 100).

Referring to FIGS. 2 and 3A-C, the string member 140 may be coupled tothe rotational motor 130 so that actuation by the motor 130 causes thestring member 140 to act upon the ratchet mechanism 150. For example,one or more full rotations of the motor 130 can be translated into atension force in the string member 140 that is applied to a pawl member152, which (in this embodiment) is pivotable to a reset position by thetension force from the string member 140. As such, the string member 140is coupled between the rotational motor 130 and the ratchet mechanism150 so as to provide a reliable and consistent adjustment of the ratchetmechanism 150. In some embodiments, the string member 140 may comprise aflexible member capable of transmitting a tension force, for example, abraided string structure (some examples are described below inconnection with FIG. 3B), a monofilament string structure, a flexibletape or ribbon structure, or the like.

The string member 140 can be arranged in a loop around two or moreguides (e.g., two guides 142 and 144 are shown in this embodiment). Sucha loop arranged can be used to optimize the location and direction ofthe tension force in the string member 140 that is applied to theratchet mechanism 150. Moreover, the loop arrangement of the stringmember may provide a force amplification effect when the string member140 is wound using the rotational motor 130, which may permit the use ofa smaller-sized motor in the pump design. Previously incorporated U.S.Provisional Application Ser. No. 60/720,411 also describes a number ofloop arrangements for the string member 140 in addition to theillustrative example depicted in FIGS. 3A-C herein.

In the embodiment shown in FIGS. 3A-C, the string member 140 starts atthe shaft 132 of the rotational motor 130, passes around a stationaryguide 142, around a second guide 144 connected to the pawl member 152,and then back to the motor 130 to form a loop arrangement. The motor 130spins such that a portion 145 the string member 140 winds upon itself,thus drawing the two guides 142 and 144 together with a forceamplification effect. In some circumstances, the force amplificationeffect of the winding string member 140 can be approximated as:

F(string)=T(motor)/r(string),

where T(motor) is the torque rating of the motor, r(string) is theradius of the string and F(string) is the subsequent pulling force onthe string. To find the total force upon the guide coupled to the pawl(F(guide)):

F(guide)=F(string)+F(String)cos(θ)−L(friction)

or reducing

F(guide)=T(motor)/r(string)[1+cos(θ)]−L(friction),

where cos(θ) describes the angle of the string with respect to parallelto the axis of the stationary guide and the drive guide and L(friction)represents the total losses associated with friction within the system.

As shown in FIG. 3B, the string member 140 may comprise braidedfilaments that are capable of enduring repeated twisting sequences ofthe string member 140. For example, the braided filaments may compriseone or more polymer materials, such as PET (e.g., DTex Dyneema materialavailable from Honeywell, Inc.). Such braided filament string membersare capable of enduring the torsion and frictional forces associatedwith undergoing thousands of cycles of twisting as described above inconnection with FIGS. 2 and 3A. The string member 140 can be formed tohave an outer diameter of about 0.02 mm to about 0.07 mm, and preferablyabout 0.05 mm. Also, in some embodiments, the string member 140 maycomprise braided filaments that are arranged around a centrally disposedthin wire filament having a diameter of about 0.02 mm or less. The thinwire filament may comprise a polymer material a metallic material havinga non-coarse outer surface. Such materials may also be capable ofenduring the repeated twisting sequences of the string member 140. Sucha construction may permit the outer filament surfaces to frictionallyengage one another during the twisting process while the filamentsurfaces contacting the centrally disposed thin wire are exposed to areduced friction load.

Referring again to FIG. 2, the string member 140 is coupled to theratchet mechanism 150, which provides incremental motion to therebyadvance the piston rod 170. The ratchet mechanism 150 includes the pawlmember 152 and the ratchet body 155, which in this embodiment is aratchet wheel having a number of teeth along its circumferentialsurface. The pawl member that is adjustable between a reset position anda forward position. For example, the rotational motor 130 may beactivated to twist the string member 140 (as previously described), andthe string member 140 then applies a tension force that adjusts the pawlmember 152 to the reset position where the pawl member 152 engages oneor more new teeth of the ratchet wheel 155. A spring device 154 is alsocoupled to the pawl member so as to urge the pawl member 152 toward theforward position. This spring bias causes the pawl member 152 to drivethe ratchet wheel 155 an incremental amount in a forward rotationaldirection as the string member 140 is untwisted.

Referring again to FIGS. 3A-3C, the adjustable pawl member 152 isconstructed in such a way as to engage the teeth of the ratchet wheel155 in a single direction (e.g., in the forward rotational direction ofthe ratchet wheel 155). In the reverse direction, a locking pawl 159prevents the ratchet wheel 155 from reverse motion. As such, theadjustable pawl member 152 can adjust from the forward position to thereset position (shown in FIG. 3A) to engage a new tooth of the ratchetwheel 155 while the ratchet wheel 155 remains in position due to thelocking pawl 159. In this embodiment, the adjustable pawl member 152 ispivotably coupled to a support plate 151 at so that the string member140 and the spring device 154 can act to pivot the pawl member betweenthe reset position and the forward position. In particular, a first endportion of the pawl member 152 may be fixedly or hingedly mounted to thesupport plate 151 while a free end portion of the pawl member 152engages the ratchet wheel 155. Also, in this embodiment, the lockingpawl 159 is fixedly coupled to the support plate 151.

The ratchet mechanism 150 can employ a set of stopper pins 153 a and 153b that limit the motion of the adjustable pawl member 152. In someembodiments, the stopper pins 153 a and 153 b can serve as locationsensors to detect when the pawl member 152 has reached the resetposition (e.g., adjacent the stopper pin 153 a) or the forward position(e.g., adjacent the stopper pin 153 b). For example, these sensors canbe optical, magnetic, or contact type sensors. The sensors may becapable of transmitting signals that indicate when the location of thepawl member 152 is detected. Such sensor signals may be transmitted tothe motor 130, to the controller device 200 (FIG. 1), or a combinationthereof. Accordingly, when the pawl member 152 reaches the stopper pin153 a (e.g., by rotation of the motor 130 that causes the string member140 to adjust the pawl member 152), a signal can indicate that the pawlmember 152 has reached the limit of its travel and the motor 130 willcease rotation in that direction (e.g., end the twisting process on thestring member 140 in that direction).

Referring again to FIG. 2 and FIGS. 3A-C, the driving force of theratchet mechanism 150 can be provided by energy stored in a potentialenergy storage device, such as the spring device 154. Thus, when theadjustable pawl 152 is driving the ratchet wheel 155 in the forwardrotational direction, the potential energy of the spring device 154 isbeing translated to kinetic energy for the motion of the pawl member 152and the ratchet wheel 155. For example, in one incremental motion cycle,the pawl member 152 may start at the reset position (as shown in FIG.3A) with the string member 140 in a twisted configuration. In responseto the controller device 200 (FIG. 1) transmitting a signal to initiatethe cycle, the rotational motor 130 may begin to rotate in a firstrotational direction that unwinds the string member 140, therebypermitting the spring device 154 to drive the pawl member 152 toward theforward position. The rotational motor 130 continues to rotate in thefirst direction so that after the pawl member 152 reaches the forwardposition (e.g., adjacent the stopper pin 153 b), the string member 140begins to twist in the opposite orientation. Such twisting of the stringmember 140 causes a tension force that overcomes the bias of the springdevice 154 and adjusts the pawl member 152 toward the reset position.After the pawl member 152 reaches the reset position (e.g., adjacent thestopper pin 153 a), the rotational motor 130 stops rotating in the firstrotational direction and the pawl member 152 remains at rest in thereset position. In the event of a second cycle, the rotational motor 130would begin the cycle by rotating in a second rotational direction(opposite the first rotational direction) so as to unwind the stringmember 140 yet again. This pattern of cycles may continue until thepiston rod 170 has reached the limit of its longitudinal travel(described in more detail below).

In other embodiments, the incremental motion cycle may begin with thepawl member 152 starting at the forward position (e.g., adjacent thestopper pin 153 b). In such circumstances, the rotation motor 130 wouldrotate in a first rotational direction to twist the string until thepawl member is moved to the reset position (as shown in FIG. 3A), andthen the rotational motor 130 would rotate in a second, oppositerotational direction to unwind the string member 140 until the pawlmember 152 returns to the forward position.

As shown in FIG. 2, the spring device 154 can be coupled to the pawlmember 152 at a first end portion and coupled to the support plate 151at a second end portion. Alternatively, as shown in FIG. 3A, the springdevice 154 can be to the pawl member 152 at a first end portion andcoupled to a part of the frame portion 114 (not directly joined to thesupport plate 151).

Referring again to FIG. 2, in some embodiments the ratchet wheel 155 canbe coupled with a worm gear 156 so that the incremental rotation of theratchet wheel 155 is translated to the worm gear 156. Such rotation ofthe worm gear 156 causes a rotation of a drive wheel 160, which isrotatably mounted to the frame portion 114 of the pump device 100. Thedrive wheel 160 includes a central aperture having an internal threadpattern therein (not shown in FIG. 2). The internal thread pattern ofthe drive wheel 160 mates is an external thread pattern on the flexiblepiston rod 170 so that the piston rod 170 is longitudinally advancedinside the plunger chamber 126 of the fluid cartridge 120. Thus, theincremental motion of provided by the ratchet mechanism 150, the stringmember 140, and the motor 130 causes the drive wheel 160 toincrementally rotate, which in turn translates to a longitudinaladvancement of the flexible piston rod 170. In one example, the drivesystem 105 can advance the piston rod 170 an increment of about 16microns or less (about 4 microns to about 12 microns, and preferablyabout 7 microns to about 8 microns) for each incremental motion cycle ofthe motor 130, string member 140, and ratchet mechanism 150 aspreviously described.

In some embodiments, the flexible piston rod 170 comprises a pluralityof segments 172 serially connected by hinge portions so that theflexible piston rod 170 is adjustable from a curved shape to a noncurvedshape. The plurality of segments 172 and the interconnecting hingeportions can be integrally formed in one piece from a moldable material,including a number of polymer materials such as Nylon or POM. In thisembodiment, the plurality of segments 172 comprise generally cylindricalsegments that each include an exterior thread pattern along at least onecylindrical surface portion. A plunger connector 178 may be coupled tothe leading end of the flexible piston rod 170 so as to abut against theplunger (not shown in FIG. 2) in the plunger chamber 126 of the fluidcartridge 120.

Still referring to FIG. 2, the flexible piston rod 170 can include ananti-rotation structure that hinders the piston rod 170 from rotatingwith drive wheel 160 (thereby allowing the rotation of the drive wheel160 to translate into a longitudinal motion of the piston rod 170). Forexample, in this embodiment, the flexible piston 170 includes alongitudinal channel 173 extending through each of the segments 172. Thelongitudinal channel 173 can engage a complementary protrusion on theframe portion 114 (not shown in FIG. 2) proximate the drive wheel 160 sothat the flexible piston rod 170 is hindered from rotating when thedrive wheel 160 turns relative to the frame portion 114. Accordingly,the longitudinal channel in each segment 172 aligns to form a keywaythat receives a mating key (e.g., a protrusion) on the frame portion114. In other embodiments, the anti-rotation structure may include aplurality of longitudinal channels 173 (with each channel capable ofengaging an associated protrusion that acts as a key to hinder rotationwhile permitting longitudinal motion), one or more flat surfaces alongeach segment 172 (with the flat surface slidably engaging acomplementary flat surface on the frame portion 114), or the like.

In the configuration illustrated in FIG. 2, the flexible piston rod 170is in a retracted state so that it has a generally curved shape, withsome or all of the cylindrical segments 172 hinged away from theadjacent segments 172. As the rod segments 172 are advanced through thedrive wheel 160, the segments 172 abut one another end-to-end so as toform a generally rigid, noncurved shape. Previously incorporated U.S.Provisional Application Ser. No. 60/720,405 also describes a number ofconfigurations for the flexible piston rod 170 in addition to theconfiguration illustrated in FIG. 2 herein.

Because the flexible piston rod 170 is adjustable from a curved shape toa noncurved shape, the overall length of the pump device can be reducedin some embodiments. For example, in a typical infusion pump that housesa straight and rigid rod, the typical infusion pump requires a packageor housing having a linear dimension sufficient to accommodate thelength of the rigid piston rod when it is at its limit of travel inwhich it is fully withdrawn from the container or cylinder. Thisrequirement for a large linear dimension can make it difficult to makethe overall size of the typical infusion pump small enough for certaindesired applications, such as, for example, wearable or implantablepumps. In a typical infusion pump having a rigid piston rod, the spacerequired to house the rigid piston rod can be described by the followingequation:

L=2t+y,  (1)

where:

-   -   “L” is the minimum overall linear dimension or length required        to support the driven member part of the device;    -   “t” is the required linear travel of an equivalent rigid driven        member; and    -   “y” is an added sum for the space required to support the        driving member part of the device.

It can be seen, therefore, that if the piston rod is a rigid, linearelement, the relative length of unused piston rod travel can potentiallydouble the overall length of the typical infusion pump housing.

In the embodiment depicted in FIG. 2, the space requirement of pumpdevice 100 having the flexible piston rod 170 is substantially less thanthe space requirement of a similar device actuated by a rigid pistonrod. This can be explained by referencing the original “spacerequirement” equation set forth above as Equation (1). In contrast tothe space requirement of a dispensing device containing a rigid pushrod,the equation for the space required for a dispensing device containing aflexible pushrod is as follows:

L=t+y+z,  (2)

where:

-   -   “L” is the minimum overall linear dimension or length required        to support the driven member part of the device;    -   “t” is the required travel of the flexible driven member        (flexible pushrod);    -   “y” is an added sum for the space required to support the        driving member; and    -   “z” is the space required to house the unused portion of the        flexible driving member.

The space required under component “z” is a function of the propertiesof the flexible piston rod 170 (e.g., the curved portion of the flexiblepiston rod 170 before it is advanced toward the fluid cartridge 120).Thus, the pump device 100 incorporating the flexible piston rod 170would require less space than the same device if it were to incorporatea non-flexible, rigid rod. In such circumstances, the overall length ofthe pump housing structure 110 can be less than twice the push rodtravel length.

It should be understood that the flexible piston rod 170 may includesegments that have a shape other than the generally cylindrical segments172. For example, in an alternative to the embodiment illustrated inFIG. 2, the segments of the flexible piston rod 170 can have a generallya square or rectangular cross-section (rather than a cylindrical shape),with teeth or a thread pattern on at least one surface thereof. In thesecircumstances, the flexible piston rod 170 may pass through a carrier inwhich the drive wheel 160 is rotatably mounted. The drive wheel 160 canhave a threaded edge, that engages the teeth of the rod segments. Thus,rotation of the drive wheel 160 causes a linear advancement of theflexible piston rod 170 along an axis that is parallel to the axis ofrotation of the drive wheel 160, while the passage of the rod segmentsthrough the carrier aligns the segments into a linear orientation.

Referring now to another embodiment of a pump device 300 as shown inFIG. 4, the drive system 305 can include a string member 340 in a looparrangement around more than two guides, such as four guide structures342, 344, 346, and 348. In these circumstances, the motion path of thestring member 340 and the orientation of the string member 340 can beconfigured to provide an efficient mechanical advantage orientationduring the desired motion of the adjustable pawl member 352. One of theguide structures 348 may be coupled to the adjustable pawl member 352while the remaining guide structures 342, 344, and 346 are coupled tothe frame portion 314 of the pump device 314. Accordingly, the stringmember 340 may have a loop configuration with more directional changescompared to the embodiments previously described in connection withFIGS. 2 and 3A.

Similar to the previously described embodiments, the pump device 300includes a housing structure 310 that defines a cavity 316 capable ofreceiving a fluid cartridge 320. The housing structure 310 may include aframe portion 314 and a detachable shell portion 312 (refer to FIG. 5)so that, when assembled, the pump device 300 can have an outerconfiguration that mates with a removable controller device 390 (referto FIGS. 6-7). In these embodiments, the drive system 305 can becontained in the housing structure 310 of the pump device 300 in acompact manner so that the pump device 300 is portable, wearable,concealable, or a combination thereof. Accordingly, a user canconveniently wear the pump device 300 on the user's skin (e.g., skinadhesive) underneath the user's clothing or carry the pump device 100 inthe user's pocket (or another portable location) while receiving themedicine dispensed from the pump device 300.

Referring to FIGS. 5-7, the pump device 300 can be part of an infusionpump system 20 in which the pump device 300 communicates with acontroller device, including but not limited to the removable controllerdevice 390 depicted in FIGS. 6-7. In this embodiment, the controllerdevice 390 includes a user interface 391 so that the operation of thepump device 300 can be readily monitored by a user. For example, theuser interface 391 may include a display 392 and two or more buttons(e.g., two buttons 394 a and 394 b are provided in this embodiment). Thepump system 20 can be a medical infusion pump system that is configuredto controllably dispense a medicine from the cartridge 320. As such, thepump device 300 can be adapted to receive a medicine cartridge 320 inthe form of a preloaded carpule that contains insulin or anothermedicine for use in the treatment of Diabetes (e.g., Byetta®, Symlin®,or others) or other injectable medicines. Similar to previouslydescribed embodiments, the pump device 300 includes a drive system 305that causes controlled dispensation of the medicine or other fluid fromthe cartridge 320. For example, the drive system 305 may incrementallyadvance a flexible piston rod 370 into a plunger chamber 326 of thecartridge 320 so that the fluid is force out the septum at the outputend 322.

In those embodiments in which the pump device 300 is connected to aremovable controller device 390, the controller device 390 cancommunicate control signals to the drive system 305 or other componentsof the pump device 300. Similar to the previously described embodiments,the controller device 390 can include a controller housing structurethat is configured to mate with a complementary portion of the pumphousing structure 310 so as to form a mechanical connection. Forexample, the controller housing structure may include a cavity thatmates with a portion of the pump housing structure 310 when thecontroller device 390 is attached to the pump device 300. In addition,the controller device 390 may include a flexible finger 317 to mate withan complementary surface of the pump housing structure 310. Further, asshown for example in FIG. 5, the pump device 300 may include one or moremagnetically attractable devices 318 a and 318 b that engage withcomplementary magnetically attractable devices of the controller device390 (not shown in FIGS. 6-7). As such, the magnetically attractabledevices 318 a and 318 b may contribute to releasably secure the pumpdevice 300 to the controller device 390. Other mechanical connectors(e.g., snap-fit connectors, magnetic connectors, surface protrusionsthat mate with female cavities, or the like) can also be implemented tojoin pump housing structure 310 with the controller device.

Still referring the FIGS. 5-7, the pump device 300 may include on ormore electrical contacts 319 that are exposed to the controller device390 and that mate with opposing electrical contacts (e.g., pads, pins,or the like) on the adjacent face of the controller device 390. In thisembodiment, the electrical contacts 319 are disposed on the detachableshell portion 312 of the pump housing structure 310 (refer to FIG. 5)and are aligned with an electrical contact device 309 mounted in theframe portion 314. It should be understood that, in other embodiments,the electrical contacts 319 may be arranged on the frame portion 314rather than on the detachable shell portion 312. In this embodiment, theframe portion 314 of the pump device may define a space 315 (refer toFIG. 4) that is capable of receiving a connection circuit 306 (refer toFIG. 5). The connection circuit 306 may be simple and inexpensive so asto facilitate a low-cost pump device 300 that is disposable. Theconnection circuit 306 may include a battery 307 or other power sourceand, optionally, a gateway circuit device 308. In some circumstances,the gateway circuit device 308 may be under the control of and directedby the control circuit in the controller device 390. The connectioncircuit 306 provides the electrical contact device 309 so as tofacilitate electrical communication with the removable controller device390. As such, the controller device 390 capable of transmittingelectrical signals to the pump device 300 and is capable of receivingfeedback signals (e.g., sensor signals) from the components in the pumpdevice 300. For example, the gateway circuit device 308 of the circuit309 may be in electrical communication (e.g., via one or more electricalwires or electrically conductive traces) with a force sensor 377 (referto FIG. 8) arranged between the plunger connector 378 that the plunger321. The force sensor 377 may comprise a force transducer or load cellthat is capable of electrically communicating an applied force. As such,the force sensor 377 can provide feedback signals to the circuit 309 (orto the control device 390 via the electrical contacts) so as to monitorthe force transmitted to the plunger 321 of the medicine cartridge 320.Such information can be used, for example, to detect if an occlusionexists in the medicine flow path. Other sensors (e.g., a pressuresensor, a flow sensor, a rotation sensor, a displacement sensor, or thelike) may be electrically connected to the circuit 306 to providefeedback signals to the circuit 306 (or to the control device 390 viathe electrical contacts). It should be understood that, in otherembodiments, the connection circuit 306 may be configured to operatewithout the gateway circuit device 308. For example, the control circuitin the removable controller device 390 may communicate via theelectrical contacts directly with a portion of the drive system 305(e.g., direct electrical communication with the motor 330), with one ormore sensors disposed in the pump device 300, and with the battery 307.

Referring to FIGS. 4-5 and 8, the pump device 300 includes a drivesystem 305 that is capable of accurately and incrementally dispensingfluid from the fluid cartridge 320 in a controlled manner. Similar tothe previously described embodiments, the drive system 305 may includethe rotational motor 330 that is coupled to the string member 340.Briefly, the rotational motor 330 can be used to act upon the stringmember 340, thereby causing the string member 340 to adjust a pawlmember 352 relative to a ratchet body 355. In this embodiment, theratchet body 355 is in the form of a ratchet wheel that is integrallyformed with a worm gear 356. Incremental rotation of the ratchet wheel355 causes rotation of a drive wheel 360, which causes the incrementallongitudinal advancement of a flexible piston rod 370. As the piston rod370 is advanced into plunger chamber 326 (e.g., defined in thisembodiment by the circumferential wall 324 of the fluid cartridge 320),the fluid in the cartridge 320 is forced from septum at the output end322. As shown in FIG. 5, when the pump device 300 is in use, the septumat the output end 322 may be pierced by a cap member 315 mounted to thehousing structure 310, which can provide fluid communication from thecartridge 320 to an infusion set tube attached to the patient. Forexample, the cap member 315 may include a penetrator device 316 a thatprovides fluid communication from the medicine cartridge 320 to a tubeconnection end 316 b. Accordingly, the drive system 305 can provide areliable and compact configuration for accurately dispensing the desiredvolume of fluid from the pump device 300. Moreover, the drive system 305may comprise few, if any, high-cost actuator components or electronics,thereby facilitating the production of a disposable and reliable pumpdevice 300. (It should be understood that FIG. 5 depicts the drivesystem 305 mounted to the frame portion 314 of the pump device 300, andFIG. 8 shows a similar view with the frame portion 314 removed forpurposes of illustrating the drive system 305 and the fluid cartridge320.)

As shown in FIG. 4, some components of the drive system 305 can beretained by the frame portion 314, a cover mount 311 that is assembledto the frame portion 314, or a combination thereof. For example, therotational motor 330, the string member 340, and the spring device 354can be assembled into the frame portion 314 and then retained by thecover mount 311. The adjustable pawl member 352, the ratchet wheel 355,and the worm gear 356 can be assembled onto and axle 351 that isintegrally formed with the frame portion 314 and then retained by thecover mount 311. A locking pawl 359 can be integrally formed with theframe portion 314 so as to align with the ratchet wheel 355 when theratchet wheel 355 is assembled onto the axle 351. Also, the drive wheel360 and an adjacent bearing 365 (to facilitate rotation of the drivewheel 360 relative to the frame portion 314) can be received in annularchannels 363 and 367, respectively, of the frame portion 314. When thecover mount 311 is assembled to the frame portion 314, the cover mount311 can restrict the radial or axial movement of the drive wheel 360while permitting forward rotation of the drive wheel 360. In anotherexample, the “unused” or retracted portion of the piston rod 370 mayrest in a channel 313 defined in the top of the cover mount 311. In sucha construction, the cover mount 311 and the frame portion 314 cancollectively permit the desired motion of the components of the drivesystem 305 while reducing the likelihood of “backlash” movement orcomponent dislodgement (which might otherwise occur, for example, whenthe pump device 300 is dropped to the ground).

Referring now in more detail to the components of the drive system 305depicted in FIGS. 9-10, the rotational motor 330 may comprise anelectrically power actuator having a rotatable output shaft 332. In thisembodiment, the rotational motor 330 can receive signals that cause theoutput shaft to rotate in a first rotational direction or in a second,opposite rotational direction. As previously described, one example of asuitable rotational motor 330 is a coreless DC motor supplied by JinlongMachinery of China. Also as previously described, the operation of therotational motor 330 can be controlled by a control device (e.g.,removable control device 200 as described in connection with FIG. 1 orthe like) via electrical signals communicated through one or moreelectrical contacts.

Still referring to FIGS. 9-10, the string member 340 may be coupled tothe rotational motor 330 so that actuation by the motor 330 causes thestring member to act upon the ratchet mechanism 350. One or more fullrotations of the motor 330 can be translated into a tension force in thestring member 340 that is applied to a pawl member 352, which (in thisembodiment) is pivoted to a reset position by the tension force from thestring member 140. As such, the string member 340 is coupled between therotational motor 330 and the ratchet mechanism 350 so as to provide areliable and consistent adjustment of the ratchet mechanism 350. In thisembodiment, the string member 340 is coupled to the motor shaft 332using a mechanical connector 333. Similar to previously describedembodiments, the string member 140 may comprise a flexible membercapable of transmitting a tension force, for example, a braided stringstructure, a monofilament string structure, a flexible tape or ribbonstructure, or the like.

The string member 340 can be arranged in a loop around two or more guidestructures (e.g., four guide structures 342, 344, 346, and 348 are shownin this embodiment). The motion path of the string member 340 and theorientation of the string member 340 can be configured to provide anefficient mechanical advantage orientation during the desired motion ofthe adjustable pawl member 352. In this embodiment, one of the guidestructures 348 is coupled to the adjustable pawl member 352 while theremaining guide structures 342, 344, and 346 are integrally formed withthe frame portion 314 of the pump device 300 (guide structures 342, 344,and 346 are shown in dotted lines to represent their location on theframe portion 314 (not shown in FIGS. 9-10)). Also, the guide structure346 exemplifies how a single guide structure can have two slidingsurfaces that oppose one another, thereby functioning similar to aconfiguration having two different guides. As described in connectionwith previous embodiments, the loop arrangement of the string member 340may provide a force amplification effect when the string member 340 iswound using the rotational motor 330.

In the embodiment shown in FIGS. 9-10, the string member 340 starts atthe shaft 332 of the rotational motor 330, passes around a first slidingsurface of the guide structure 346, around a second guide structure 342,around a third guide structure 348 connected to the adjustable pawlmember 352, around a fourth guide structure 344, around a second slidingsurface of the guide structure 346, and then back to the motor 330 toform the loop arrangement. As shown in FIG. 10, when the motor 330rotates, a portion 345 the string member 340 twists upon itself, thusdrawing the guide structure 348 toward the stationary guide structures342 and 344. The orientation of the stationary guide structures 342 and344 relative to the guide structure 348 (connected to the pawl member352) can be configured to provide an efficient mechanical advantage forthe tension force applied by the string member 340 during the desiredmotion of the adjustable pawl member 352.

The string member 340 is coupled to the ratchet mechanism 350, whichprovides incremental motion to thereby advance the piston rod 370. Theratchet mechanism 350 includes the pawl member 352 and the ratchet body355, which in this embodiment is a ratchet wheel having a number ofteeth along its circumferential surface. The pawl member 352 isadjustable between a reset position (refer to FIG. 10) and a forwardposition (refer to FIG. 9). For example, the rotational motor 330 may beactivated to twist the string member 340, and the string member 340 thenapplies a tension force that adjusts the pawl member 352 to the resetposition in which the pawl member 352 grabs a new tooth of the ratchetwheel 335 (refer to FIG. 10). In this embodiment, the adjustable pawlmember 352 is pivotably coupled to about the axis of the axle 351 (referto FIG. 4) that receives the ratchet wheel 355 and the worm gear 356.

A spring device 354 is also coupled to the pawl member 352 so as to urgethe pawl member 352 toward the forward position (refer to FIG. 9). Inthis embodiment, the spring device 354 is in the form of a leaf springthat is fixed to the frame portion 314 (refer to FIG. 4) at a first endportion and that is engaged with an abutment protrusion 357 of the pawlmember 352 at a second end portion. Thus, as shown in FIG. 10, when thepawl member 352 is adjusted to the reset position, the spring device 354is flexed and stores potential energy that urges the pawl member 152 toreturn to the forward position (refer to FIG. 9) and thereby drive theratchet wheel 355 in a forward rotational direction. As previouslydescribed, a locking pawl 359 coupled to the frame portion 314 (refer toFIG. 4) prevents the ratchet wheel 355 from reverse motion. As such, theadjustable pawl member 352 can adjust from the forward position (referto FIG. 9) to the reset position (refer to FIG. 10) to engage a newtooth of the ratchet wheel 355 while the ratchet wheel 355 remains inposition due to the locking pawl 359.

It should be understood that the drive system 305 can employ a set ofstopper pins (similar to previously described embodiments) that limitthe motion of the adjustable pawl member 352 or that serve as locationsensors to indicate when the pawl member 352 has reach the resetposition or the forward position. For example, these sensors can beoptical, magnetic, or contact type sensors. The sensors may be capableof transmitting signals that indicate when the location of the guidestructure 348 or the pawl member 352 is detected. Such sensor signalsmay be transmitted to the motor 330, to the controller device, or acombination thereof.

Still referring to FIGS. 9-10, in some embodiments the ratchet wheel 355can be integrally formed with the worm gear 356 so that the incrementalrotation of the ratchet wheel 355 is translated to the worm gear 356.Such rotation of the worm gear 356 causes a rotation of a drive wheel360, which is rotatably mounted to the frame portion 314 of the pumpdevice 300. Similar to previously described embodiments, the drive wheel360 includes a central aperture having an internal thread patterntherein (not shown in FIGS. 9-10), which mates is an external threadpattern on the flexible piston rod 370. Thus, the incremental motionprovided by the ratchet mechanism 350, the string member 340, and themotor 330 causes the drive wheel 360 to incrementally rotate, which inturn translates to a linear advancement of the flexible piston rod 370.

Accordingly, in some embodiments, the piston rod 370 may undergo onlyforward or positive displacement as a result of drive system 305. Forexample, the drive system 305 substantially hinders the piston rod 370from retracting or “backing up” in response to fluid pressure in themedicine cartridge 320 or other reversal forces. In such circumstances,the flexible piston rod 370 can be retracted only upon disassembly ofthe pump device 300 (e.g., to disengage the gears or the ratchetmechanism). In those embodiments in which the pump device 300 isintended to be disposable, the non-retractable piston rod configuration(due to the drive system 305) may facilitate a “one time use” disposablepump device, thereby reducing the likelihood of failure due tonon-intended repeated use of the disposable pump device.

The flexible piston rod 370 comprises a plurality of segments 372serially connected by hinge portions so that the flexible piston rod 370is adjustable from a curved shape to a noncurved shape. As previouslydescribed, the plurality of segments 372 and the interconnecting hingeportions can be integrally formed in one piece from a moldable material,including one or more polymer materials such as Nylon or POM. In thisembodiment, the plurality of segments 372 comprise generally cylindricalsegments that each include an exterior thread pattern along at least onecylindrical surface portion. A plunger connector 378 may be coupled tothe leading end of the flexible piston rod 370 so as to abut against orconnect with the plunger 321 in the plunger chamber 326 of the fluidcartridge 320. Previously incorporated U.S. Provisional Application Ser.No. 60/720,405 also describes a number of configurations for theflexible piston rod 370 in addition to the configuration illustrated inFIGS. 9-10 herein.

Referring now to FIGS. 11A-C, the incremental motion cycle of the drivesystem 305 may include rotation of the motor 330 so that the stringmember 340 transitions from a twisted state, to an untwisted state, andthen again to a twisted state. Such a transition of the string member340 can cause the pawl member 352 to adjust from the reset position(refer to FIG. 11A), to the forward position (refer to FIG. 11B), andback to the reset position (refer to FIG. 11C). The adjustment of thepawl member 352 from the reset position to the forward position drivesthe ratchet wheel 355 and worm gear 356, which incrementally rotates thedrive wheel 360 and thereby advances the flexible piston rod 370 alongitudinal increment distance 379 (refer to FIG. 11B). In one example,the drive system 305 can advance the piston rod 370 a longitudinalincrement distance 379 of about 16 microns or less (about 4 microns toabout 12 microns, and preferably about 7 microns to about 8 microns) foreach incremental motion cycle of the motor 330, string member 340, andratchet mechanism 350 as previously described herein.

As shown in FIGS. 11A-C, some embodiments of the motor 330 may include amandrel 334 extending axially from the mechanical connector 333 or themotor shaft 332. The mandrel can be arranged so that the string member340 is configured to twist around the mandrel 334 in response torotation by the motor shaft 332. The frictional wear upon the stringmaterial may be reduced because the string member engages and twistsaround the mandrel 334 rather than engaging an opposing string materialsurface and twisting upon itself.

Referring to now FIG. 11A, in this embodiment of the incremental motioncycle, the pawl member 352 begins at the reset position with the stringmember 340 in a twisted configuration at string portion 345. Aspreviously described, the string portion 345 is twisted around themandrel 334 that extends axially from the motor 330. When the adjustablepawl member 352 is in the reset position as shown in FIG. 11A, it iscapable of engaging a tooth of the ratchet wheel 355.

Referring to FIG. 11B, in response to the controller device transmittinga signal to initiate the cycle, the rotational motor 330 may begin torotate in a first rotational direction that unwinds the string member340, thereby permitting the spring device 354 to drive the pawl member352 toward the forward position (refer to FIG. 11B). When the adjustablepawl 352 is driving the ratchet wheel 355 in the forward rotationaldirection, the potential energy of the spring device 354 is beingtranslated to kinetic energy for the motion of the pawl member 352 andthe ratchet wheel 355. Such an adjustment of the pawl member 352 fromthe reset position to the forward position drives the ratchet wheel 355and the integrally formed worm gear 356. The incremental rotation of theworm gear 356 results in an incremental rotation by the drive wheel 360,which advances the flexible piston rod 370 the longitudinal incrementdistance 379. Such an incremental advancement of the flexible piston rod370 may cause a predetermined volume of fluid to be dispensed from thecartridge 320 (FIG. 4).

Referring to FIG. 11 C, the rotational motor 330 continues to rotate inthe first rotational direction so that after the pawl member 352 reachesthe forward position, the string member 340 begins to twist in theopposite orientation. As previously described, the string member 340 istwisted around the mandrel 334 that extends axially from the motor 330.Such twisting of the string member 340 causes a tension force thatovercomes the bias of the spring device 354 and adjusts the pawl member352 toward the reset position. When the adjustable pawl member 352reaches the reset position, as shown in FIG. 11C, the pawl member iscapable of engaging a new tooth of the ratchet wheel 355. The lockingpawl 359 (shown in FIG. 4) prevents the ratchet wheel 355 from rotatingin a reverse (non-forward) rotational direction while the adjustablepawl member 352 is shifting back to the reset position. Such anadjustment of the pawl member 352 back to the reset position causes thespring device 354 to flex (as shown in FIG. 11C), thereby storingpotential energy to drive the adjustable pawl member 352 and ratchetwheel 355 in a subsequent cycle. After the pawl member 352 reaches thereset position, the rotational motor 330 stops rotating in the firstrotational direction and the pawl member 352 remains at rest in thereset position (refer to FIG. 11C). In the event of a subsequent cycle,the rotational motor 330 would begin the cycle by rotating in a secondrotational direction (opposite the first rotational direction) so as tounwind the string member 340 yet again. This pattern of cycles maycontinue until the piston rod 370 has reached the limit of itslongitudinal travel.

It should be understood, that in other embodiments, the incrementalmotion cycle may begin with the pawl member 352 starting at the forwardposition (refer to FIG. 11B). In such circumstances, the rotation motor330 would rotate in a first rotational direction to twist the stringuntil the pawl member is moved to the reset position (refer to FIG.11C), and then the rotational motor 330 would rotate in a second,opposite rotational direction to unwind the string member 340 until thepawl member 352 returns to the forward position (refer again to FIG.11B).

Similar to the previously described embodiments, the string member 340may comprise braided filaments that are capable of enduring repeatedtwisting sequences of the string member 340. The braided filaments maycomprise a polymer such as PET. Such braided filament string members arecapable of enduring the torsion and frictional forces associated withundergoing thousands of cycles of twisting as described above inconnection with FIGS. 11A-C. The string member 340 can be formed to havean outer diameter of about 0.02 mm to about 0.07 mm, and preferablyabout 0.05 mm. Also, in some embodiments, the string member 340 maycomprise braided filaments that are arranged around a centrally disposedthin wire filament (e.g., comprising a polymer material or a metallicmaterial) having a diameter of about 0.02 mm or less, which is alsocapable of enduring the repeated twisting sequences of the string member340. Such a construction may permit the outer filament surfaces tofrictionally engage one another during the twisting process while thefilament surfaces contacting the centrally disposed thin wire areexposed to a reduced friction load.

Referring now to FIGS. 12-14, some embodiments of a pump device 400 caninclude a string member and a rotational motor like the previouslydescribed embodiments, except that the string member 440 is configuredto wind (or unwind or both) around a spindle device. Such aconfiguration may reduce the torsion and friction loads upon the stringmember material while providing a tension force to adjust the ratchetmechanism. Moreover, the spindle configuration may further reduce thespace requirements for drive system in the pump housing, therebyproviding a reliable and compact infusion pump system that is portableand wearable by the user.

Referring to FIG. 12, a ratchet mechanism 450 that is configured toassemble within a pump device (similar to the ratchet mechanism 150 inpump device 100 described in connection with FIG. 3A) is adjusted by astring member 440 that can wind around a spindle device 442. The ratchetmechanism 450, string member 440, spindle device 442, and motor 430 canbe part of a drive system for the pump device (similar to the drivesystem 105 of the pump device 100 described in connection with FIG. 2)that provides a reliable and consistent configuration for accuratelydispensing the desired volume of fluid from the infusion pump device.Also, similar to the previously described embodiments, the drive systemincluding the string member 440, the motor 430, and the spindle device442 may comprise few, if any, high-cost components, thereby facilitatingthe production of a disposable infusion pump device. Because the pumpdevice may house the drive system in a compact manner, the pump devicecan be portable, wearable, and readily concealable by the user.

As shown in FIG. 12, the spindle device 442 can be coupled to arotational motor 430 so that the spindle device 442 rotates with themotor shaft. A string member 440 can be attached to the spindle device442 so that the string member 440 winds or unwinds around the spindledevice 442 in response to the rotation of the motor 430. Similar topreviously described embodiments, the string member 440 may comprise aflexible member capable of transmitting a tension force, for example, abraided filament structure, a monofilament string structure, a flexibletape or ribbon structure, or the like. For example, in some embodiments,the string member 440 may comprise a flexible tape material havinggenerally flat opposing surfaces, thereby permitting the tape materialto be wrapped around itself when being wound on the spindle device 442.

The string member 440 is also coupled to the ratchet mechanism 450,which provides incremental motion to thereby advance the piston rod (notshown in FIG. 12). The ratchet mechanism 450 includes the pawl member452 and the ratchet body 455, which in this embodiment is a ratchetwheel having a number of teeth along its circumferential surface. Thepawl member 452 is adjustable between a reset position (refer to FIG.12) and a forward position. For example, the rotational motor 430 may beactivated to rotate the spindle device 442 and thereby wind the stringmember 440 (as previously described), and the string member 440 thenapplies a tension force that adjusts the pawl member 452 to the resetposition. In the reset position, the pawl member 452 can engage one ormore new teeth of the ratchet wheel 455. A spring device 454 is alsocoupled to the pawl member 452 so as to urge the pawl member 452 towardthe forward position. This spring force causes the pawl member 452 todrive the ratchet wheel 455 an incremental amount in a forwardrotational direction. Similar to the embodiments previously described inconnection with FIG. 3A, a locking pawl 459 prevents the ratchet wheel455 from reverse motion. As such, the adjustable pawl member 452 canadjust from the forward position to the reset position (shown in FIG.12) to engage a new tooth of the ratchet wheel 455 while the ratchetwheel 455 remains in position due to the locking pawl 459.

In this embodiment, the ratchet mechanism 450 can employ a set ofstopper pins (as previously described) that limit the motion of theadjustable pawl member 452. In some embodiments, the stopper pins canserve as location sensors to detect when the pawl member has reach thereset position or the forward position. For example, these sensors canbe optical, magnetic, or contact type sensors.

Accordingly, in one incremental motion cycle, the pawl member 452 maystart at the reset position (as shown in FIG. 12) with the string member440 wound around the spindle device 442. In response to the controllerdevice (not shown in FIG. 12) transmitting a signal to initiate thecycle, the rotational motor 430 may begin to rotate in a firstrotational direction that unwinds the string member 440 from the spindledevice 442, thereby permitting the spring device 454 to force the pawlmember 452 toward the forward position. The rotational motor 430continues to rotate in the first rotational direction so that after thepawl member 452 reaches the forward position, the string member 440begins to wind around the spindle device 442 in the oppositeorientation. Such winding of the string member 440 causes a tensionforce that overcomes the bias of the spring device 454 and adjusts thepawl member 452 toward the reset position. After the pawl member reachesthe reset position, the rotational motor 430 stops rotating in the firstrotational direction and the pawl member 452 remains at rest in thereset position. In the event of a second cycle, the rotational motor 430would begin the cycle by rotating in a second rotational direction(opposite the first rotational direction) so as to unwind the stringmember 440 from the spindle device 442 yet again.

In other embodiments, the incremental motion cycle may begin with thepawl member 452 starting at the forward position. In such circumstances,the rotational motor 430 would rotate in a first rotational direction towind the string member 440 around the spindle device until the pawlmember 452 is moved to the reset position (as shown in FIG. 12), andthen the rotational motor 430 would rotate in a second, oppositerotational direction to unwind the string member 440 from the spindledevice 442 until the pawl member 452 returns to the forward position.

Referring now to another embodiment of a pump device 500 as shown inFIGS. 13-14, the drive system 505 can include a string member 540 thatis configured to wrapped around a spindle device 542. In thesecircumstances, the orientation of the string member 540 can beconfigured to provide an efficient mechanical advantage during thedesired motion of the adjustable pawl member 552. Moreover, such aconfiguration may reduce the torsion and friction loads upon the stringmember material and may further reduce the space requirements for drivesystem 505 of the pump device 500. Similar to previously describedembodiments, the string member 540 may comprise a flexible membercapable of transmitting a tension force, for example, a braided filamentstructure, a monofilament string structure, a flexible tape or ribbonstructure, or the like. For example, in some embodiments, the stringmember 540 may comprise a flexible tape material having generally flatopposing surfaces, thereby permitting the tape material to be wrappedaround itself when being wound on the spindle device 542.

Similar to the previously described embodiments, the pump device 500includes a housing structure 510 that defines a cavity 516 capable ofreceiving a fluid cartridge (not shown in FIGS. 13-14). The housingstructure 510 may include a frame portion 514 and a detachable shellportion (removed from FIGS. 13-14 for purposes of illustration) so that,when assembled, the pump device 500 can have an outer appearance similarto that of pump device 300 depicted in FIG. 5. In these embodiments, thedrive system 505 can be contained in the housing structure 510 of thepump device 500 in a compact manner so that the pump device 500 isportable, wearable, concealable, or a combination thereof. Similar topreviously described embodiments, the pump device 500 can be part of aninfusion pump system in which the pump device communicates with acontroller device, including but not limited to the removable controllerdevice 390 described in connection with FIGS. 5-7. The controller devicecan communicate control signals to the drive system 505 or othercomponents of the pump device 500. For example, the pump device 500 mayinclude on or more electrical contacts that are exposed to thecontroller device and that mate with opposing electrical contacts (e.g.,pads, pins, or the like) on the adjacent end of the controller device.In this embodiment, the pump system is a medical infusion pump systemthat is configured to controllably dispense a medicine. As such, thepump device 500 can be adapted to receive a medicine cartridge in theform of carpule that contains insulin or another medicament for use inthe treatment of Diabetes (e.g., exenatide, Byetta™, or others), orother injectable medicines.

Still referring to FIGS. 13-14, the pump device 500 includes a drivesystem 505 that is capable of accurately and incrementally dispensingfluid from the fluid cartridge in a controlled manner. Similar to thepreviously described embodiments, the drive system 505 may include arotational motor 530 that is coupled to a string member 540. Briefly,the rotational motor 530 can be used to wind (or unwind or both) thestring member 540 around a spindle device 542, which causes the stringmember 540 to adjust a pawl member 552 relative to a ratchet body 555.In this embodiment, the ratchet body 555 is in the form of a ratchetwheel that is integrally formed with a worm gear 556. Incrementalrotation of the ratchet wheel 555 causes rotation of a drive wheel 560,which causes the incremental linear advancement of a flexible piston rod570. As the piston rod 570 is advanced in the forward longitudinaldirection, fluid dispenses from the pump device 500. Accordingly, thedrive system 505 can provide a reliable and compact configuration foraccurately dispensing the desired volume of fluid from the pump device500. Moreover, the drive system 505 may comprise few, if any, high-costactuator components or electronics, thereby facilitating the productionof a disposable and reliable pump device 500.

Referring to FIG. 14 (note that the frame portion 514 has been removedfrom FIG. 14 for purposes of illustration), the string member 540 iscoupled to the ratchet mechanism, which provides incremental motion tothereby advance the piston rod 570. The ratchet mechanism includes thepawl member 552 and the ratchet body 555, which in this embodiment is aratchet wheel having a number of teeth along its circumferentialsurface. The pawl member 552 is adjustable between a reset position anda forward position (refer to FIG. 14). For example, the rotational motor530 may be activated to wind the string member 540 around the spindledevice 542, and the string member 540 then applies a tension force thatadjusts the pawl member 552 to the reset position in which the pawlmember 552 grabs a new tooth of the ratchet wheel 555. A spring device554 is also coupled to the pawl member 552 so as to urge the pawl member552 toward the forward position. In this embodiment, the spring device554 is a leaf spring that is fixed to the frame portion 514 (refer toFIG. 13) at a first end portion and that is engaged with an abutmentprotrusion 557 of the pawl member 552 at a second end portion. Thus,when the pawl member 552 is adjusted to the reset position, the springdevice 554 is increasingly flexed and thereby stores potential energythat urges the pawl member 552 to return to the forward position.Similar to previously described embodiments, a locking pawl coupled tothe frame portion 514 (refer to FIG. 13) prevents the ratchet wheel 555from reverse motion. As such, the adjustable pawl member 552 can adjustfrom the forward position to the reset position to engage a new tooth ofthe ratchet wheel 555 while the ratchet wheel 555 remains in positiondue to the locking pawl 559.

In this embodiment, the ratchet wheel 555 is integrally formed with theworm gear 556 so that the incremental rotation of the ratchet wheel 555is translated to the worm gear 556. Such rotation of the worm gear 556causes a rotation of a drive wheel 560, which is rotatably mounted tothe frame portion 514 using a bearing 565. Similar to previouslydescribed embodiments, the drive wheel 560 includes a central aperturehaving an internal thread pattern therein (not shown in FIGS. 13-14),which mates with an external thread pattern on the flexible piston rod570. Thus, the incremental motion provided by the ratchet mechanism 550,the string member 540, and the motor 530 causes the drive wheel 560 toincrementally rotate, which in turn translates to a linear advancementof the flexible piston rod 570. A plunger connector 578 may be coupledto the leading end of the flexible piston rod 570 so as to abut againstor connect with the plunger in the fluid cartridge.

Still referring to FIG. 14, the incremental motion cycle of the drivesystem 505 may include rotation of the motor 530 so that the stringmember 540 transitions from a wrapped state (e.g., wound around thespindle device 542), to an unwrapped state, and then to a wrapped state.Such a transition of the string member 540 can cause the adjustable pawlmember 552 to transition from the reset position, to the forwardposition (refer to FIG. 14), and back to the reset position. Aspreviously described, the adjustment of the pawl member 552 from thereset position to the forward position drives the incremental rotationof the drive wheel 560, which advances the flexible piston rod 570 alongitudinal increment distance. In one example, the drive system 505can advance the piston rod 570 a longitudinal increment distance ofabout 16 microns or less (about 4 microns to about 12 microns, andpreferably about 7 microns to about 8 microns) for each incrementalmotion cycle of the motor 530, string member 540, and ratchet mechanism550 as previously described herein. It should be understood, that inother embodiments, the incremental motion cycle may begin with the pawlmember 552 starting at the forward position (refer to FIG. 14). In suchcircumstances, the rotation motor 530 would rotate in a first rotationaldirection to wind the string member 540 around the spindle device 542until the pawl member 552 is moved to the reset position, and then therotational motor 530 would rotate in a second, opposite rotationaldirection to unwind the string member 540 until the pawl member 552returns to the forward position.

A number of embodiments of the invention have been described.Nevertheless, it will be understood that various modifications may bemade without departing from the spirit and scope of the invention.Accordingly, other embodiments are within the scope of the followingclaims.

1. A medical infusion pump system, comprising: a pump device including:a pump housing that defines a space to receive a medicine cartridge, acap device to secure with the pump housing to enclose the medicinecartridge in the pump housing when the medicine cartridge is received inthe space the of the pump housing, and a pump drive system to dispensemedicine from out of the pump device, the pump drive system including: apiston rod to advance toward the medicine cartridge and force themedicine from the pump device; a mechanism to advance the piston rodtoward the medicine cartridge, the mechanism comprising a pawl and aratchet member, the pawl positioned to engage one or more teeth of theratchet member, wherein the pawl is adjustable between a first positionand a second position to move the ratchet member in a forward directionso as to cause the piston rod to advance toward the medicine cartridge;and a battery-powered motor having an output that rotates one or morefull rotations to cause the pawl to adjust toward one of the firstposition or the second position; and a removable controller device thatis removably attachable to the pump device so that a mechanicalconnection and an electrical connection is formed between the pumpdevice and the controller device, the controller device including:control circuitry that communicates electrical signals to the pump drivesystem via the electrical connection, and a user interface display. 2.The medical infusion pump system of claim 1, wherein removablecontroller device controls the output of the motor to alternate betweenrotation in a first rotational direction and rotation in a secondrotational direction.
 3. The medical infusion pump system of claim 1,wherein the drive system further includes a bias member coupled to thepawl to drive the pawl toward the second position and move the ratchetmember in the forward direction.
 4. The medical infusion pump system ofclaim 1, wherein the piston rod of the pump drive system comprises aflexible piston rod that is advanced in a longitudinal direction by anincremental distance in response to movement of the ratchet member inthe forward direction.
 5. The medical infusion pump system of claim 1,wherein the pump drive system comprises a string member coupled to theoutput of the battery-powered motor and coupled to the pawl.
 6. Themedical infusion pump system of claim 5, wherein the string member istwisted by the one or more rotations of the output of the motor andthereby urges the pawl toward the reset position.
 7. The medicalinfusion pump system of claim 5, wherein the one or more rotations bythe output of the motor causes the string member to apply a tensionforce to the pawl.
 8. The medical infusion pump system of claim 1,wherein the pawl comprises a pivotable body and the ratchet membercomprises a ratchet wheel having said teeth along an outer periphery ofthe ratchet wheel.
 9. A method of controlling a medical infusion pumpsystem, comprising: receiving via a user interface of a controllerdevice user input related to dispensing medicine, the controller devicebeing removably attachable to a pump device to form a mechanicalconnection and an electrical connection between the pump device and thecontroller device; activating a battery-powered motor of a pump drivesystem housed inside the pump device to rotate one or more fullrotations in response to one or more electrical signals communicatedfrom the controller device via the electrical connection, the pump drivesystem further comprising: a piston rod, and a mechanism to advance thepiston rod toward the medicine housed in the pump device, the mechanismcomprising a pawl and a ratchet member, the pawl positioned to engageone or more teeth of the ratchet member, wherein the pawl is adjustablebetween a first position and a second position to move the ratchetmember in a forward direction so as to cause the piston rod to advancetoward the medicine, wherein the one or more full rotations of thebattery-powered motor cause the pawl to adjust toward one of the firstposition or the second position; and advancing the piston rod todispense a portion of the medicine from the pump device.
 10. The methodof claim 9, wherein the step of activating a battery-powered motorcomprises activating the battery-powered motor to rotate one or morefull rotations in a first rotational direction and one or more fullrotations in a second rotational direction.
 11. The method of claim 9,wherein the pump drive system further includes a bias member coupled tothe pawl to drive the pawl toward the second position and move theratchet member in the forward direction.
 12. The method of claim 9,wherein the piston rod of the pump drive system comprises a flexiblepiston rod that is advanced in a longitudinal direction by anincremental distance in response to movement of the ratchet member inthe forward direction.
 13. The method of claim 9, wherein the pump drivesystem comprises a string member coupled to the output of thebattery-powered motor and coupled to the pawl.
 14. The method of claim13, wherein the string member is twisted by the one or more rotations ofthe output of the motor and thereby urges the pawl toward the resetposition.
 15. The method of claim 13, wherein the one or more rotationsby the output of the motor causes the string member to apply a tensionforce to the pawl.
 16. The method of claim 9, wherein the pawl comprisesa pivotable body and the ratchet member comprises a ratchet wheel havingsaid teeth along an outer periphery of the ratchet wheel.